Tray for foodstuffs

ABSTRACT

A tray of sheet paper material for containing foodstuffs in which there is a bottom and a side wall emerging therefrom and defining, in cooperation with said bottom, a holding space facing upwardly under use conditions of the tray; the side wall is defined by alternated straight portions and curved portions both having upwardly-facing flat surfaces ( 7, 9 ) to allow engagement of a closing film heat-sealed thereto; the straight portions ( 4 ) also have reinforcing tabs in engagement at the lower part thereof with the flat surfaces ( 7 ) and the tray is also provided with a reinforcing edge ( 10 ) folded downwardly along the whole upper perimeter of the container itself. The tray thus made has excellent features of mechanical resistance to deformations.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to a tray for containing foodstuffs and tothe method of producing the same. In detail, the invention relates to acontainer of paper material intended for conservation and possiblecooking of foods such as lasagne, prepackaged dishes, etc.

It is known that there is on the market a great number of foodcontainers made of paper material and adapted to allow conservationand/or cooking of products of different nature.

Containers defined by a flat bottom wall of substantially rectangularshape from which a side wall emerges and is adapted to delimit, incooperation with the bottom wall, a holding space set to receive theappropriate food are well known.

Such a holding tray is then provided, at the upper part thereof, with anoutwardly-bent edge capable of defining a continuous flat surface overthe whole upper periphery of the container.

The flat surface (with an extension parallel to that of the bottom wall)defined by the bent edge is susceptible of enabling closure of theholding space by use of a plastic film for example, heat-sealed alongthe whole peripheral surface.

While these trays (obtained by a series of bending operations insuccession starting from a flat sheet of paper material) have beenwidely spread and used, the same products are not however devoid oftechnical and/or operating limits and drawbacks.

The containers of the described type have a weak resistance todeformations, in particular to deformations taking place at the sidewalls. Actually, these containers do not offer a satisfactory resistanceagainst forces directed transversely of the side walls, which results inthe risk that deformations due to handling of the container alreadyfilled with the foodstuff may cause escape of the product.

The above mentioned drawbacks have been at least partly eliminated byproviding a tray as previously described applying a further rim of papermaterial, by gluing, close to the sealing surface so as to make the bentedge a two-layered edge and therefore increase the resistance todeformations transversely of the side wall.

This solution too however, has many drawbacks. First of all the presenceof glue and elements of different nature in engagement with each othercan cause foodstuff contamination and also enable the humidity containedin the food to penetrate the paper fibres wetting them and thereforegreatly lowering the resistance to stresses of same container.

On the other hand, it is to be noted that, from the standpoint of themanufacturing costs, arrangement of this further reinforcing element iscarried out starting from a flat sheet of paper material suitably cutout only a minimum portion of which is used whereas most of the materialis to be discarded.

SUMMARY OF THE INVENTION

Accordingly, the present invention aims at substantially solving all thementioned drawbacks. It is a first aim of the invention to devise a trayof paper material that is provided with the necessary structure featuresenabling to withstand the transverse deformations of the side wallsthereof.

Another aim of the present invention is to obtain a container forfoodstuffs made of paper material in which the food cannot come intocontact with glue or the like and also cannot transfer its humidity tothe cellulose fibres so as to maintain the mechanical-resistancefeatures of said fibres as much as possible unimpaired.

It is a further aim of the invention to obtain a product of papermaterial of reduced costs by decreasing or eliminating the workingrejects as much as possible.

It is a still further aim of the invention to obtain trays forcontaining foodstuffs that are of simple manufacture and require alimited number of manufacturing operations.

The foregoing and further aims that will become more apparent in thecourse of the following description are substantially achieved by a trayfor containing foodstuffs, and by a method for manufacture of same asrecited in the appended claims.

BRIEF DESCRIPTION OF THE DRAWING

Further features and advantages will be best understood from thedetailed description of a preferred but not exclusive embodiment of theinvention with reference to the accompanying drawings, in which:

FIG. 1 shows a plan development of a tray in accordance with the presentinvention;

FIG. 1A shows the plan development of an alternative embodiment of atray in accordance with the invention;

FIG. 2 shows an intermediate passage of the production steps of the trayin accordance with the present invention;

FIG. 3 is a view of the tray in accordance with the invention;

FIGS. 4 and 5 show a section of the side wall of the tray at a straightportion of the side wall and a curved portion of the same side wall,respectively; and

FIG. 5A shows the section of a curved portion of a tray in accordancewith an alternative embodiment of same.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings, a tray for containing foodstuffs hasbeen generally identified with reference numeral 1.

The container is fully made of paper material starting from a flat sheetof the type shown in FIG. 1, as better clarified in the following.

In detail, the tray is intended for conservation and possible cooking offoodstuffs, such as prepackaged products for example.

As can be seen from the accompanying drawings, the tray has a flatbottom wall 2 from which a side wall 3 emerges that, in cooperation withsaid bottom wall 2, defines a holding space 6 set to receive theappropriate food.

While not essential, bottom 2 can be of a substantially rectangularshape the sides of which are connected with each other by short curvedsections.

In this way the side wall 3 emerging from said bottom will showrespective straight portions 4 emerging from the straight sections ofbottom 2, alternated with curved portions 5 (defining the tray corners)emerging from the respective curved sections of said bottom 2.

Since the tray is fully made starting from a flat sheet, the curvedportions 5 will obviously have excess material that will be formed intopleats or the like (see FIGS. 2 and 3).

Therefore, the straight and curved portions 4, 5 of the side wall 3define an inner holding surface 11 without a break. In other words, dueto the fact that the present tray is obtained starting from a flatsheet, no cracks, cuts or the like that may give rise to leakage of theproduct contained therein can exist on the side wall or the innerholding surface.

The upper region of the side wall 3 where the different folded edges aredefined is now examined, and the following can be noticed as regards theengagement surfaces for reinforcement of the tray itself.

First of all at least one straight portion 4 of the side wall 3comprises a flat surface 7 facing upwardly and having a flat developmentsubstantially parallel to the bottom development.

A reinforcing tab 8 (see FIG. 2 in particular) is designed to beassociated during the production steps at the lower part of the traywith the flat surface 7, as visible in the section in FIG. 4.

The curved portion of the side wall 3 too comprises a respective flatsurface 9 facing upwardly as well, and having a development parallel tothe development of the bottom wall.

Obviously, due to the presence of excess material (since the tray ismanufactured starting from a flat sheet of paper material), the flatsurface 9 too will have respective pleated or crimped regions, or thelike.

Finally, at least one straight portion 4 and one curved portion 5 of theside wall 3 will have respective outer reinforcing edges 10 foldedtransversely (for example at right angles) with respect to the flatsurfaces 7, 9 (FIGS. 3, 4 and 5).

As can be easily understood looking at the accompanying drawings, eachstraight portion 4 has the respective reinforcing tab 8 joined to therespective flat-surface 7 without a break; tab 8 will be then foldeddown against the lower side of surface 7 when the tray is assembled.

The reinforcing edge 10 too extends over the whole side perimeter of thetray without a break and in such a manner that an optimal resistance tostresses transverse to the side wall is ensured.

Therefore, taking into account the above described structure, the sidewall will be in section as shown in FIGS. 4 and 5. In particular, thereinforcing edge 10 will be a two-layered edge at the straight portions(see FIG. 4) and will consist of one layer alone at the curved portions5 (see FIG. 5).

In addition, the presence of the flat surfaces 7 and 9 along the wholeupper edge of the tray allows engagement of possible closing filmstherewith, which films are heat-sealed for conservation of thefoodstuff.

Advantageously, the tray has no other elements of paper material addedby gluing, stapling or the like. In other words, arrangement of suitablereinforcing rims or other elements is not required in order to definethe structural-resistance features of the container or modify thecontainer structure.

With reference to the alternative embodiment shown in FIG. 1A,reinforcing tabs 8 can be provided with end portions 8A that, oncefolded back, are adapted to abut against the lower side of the flatsurfaces 9 defined by the curved portions. In this way the four traycorners are reinforced as well and they show in transverse section adouble wall (see FIG. 5A).

After describing the invention from a structural point of view, themethod of manufacturing the tray shown in FIG. 3 is the following.

First of all a flat sheet of paper material having the appropriate sizeand basis weight is set and a portion of the type shown in FIG. 1 is cutout therefrom.

Then a drawing operation is executed on the sheet in order to definebottom 2 and the side wall 3 emerging from said bottom. In particular,bending at least along line A in FIG. 1 is carried out. Then a bendingoperation along the chain line denoted at B in FIG. 1 is carried out(obviously this operation can be executed simultaneously with thepreceding one) in order to define an upwardly-facing flat surface 7, 9at an upper region of the side wall.

Once the above operations have been completed, the flat sheet has passedfrom the condition shown in FIG. 1 to the condition shown in FIG. 2.Under this situation, folding of a predetermined number of reinforcingtabs 8 against the lower side of the flat surface 7 is carried out ateach of the straight sides (folding line C in FIG. 1). Optionally thesetabs can be glued to the lower side of the flat surface 7.

Then a further bending operation at the upper region of the side wall isexecuted in order to obtain the reinforcing edge 10 transverse to theflat surfaces 7, 9 over the whole perimeter of the side wall 3 so thatthe configuration shown in FIG. 3 is reached and the finished product isobtained (folding lines D, E in FIG. 1).

Following the above described bending and folding operations, at thestraight portions an edge of the type shown in section in FIG. 4 isobtained and at the curved portions an edge of the type shown in sectionin FIG. 5 is obtained.

The invention achieves important advantages.

First of all the tray in reference is obtained starting from a singleflat sheet of paper material. In other words, no waste of paper materialexists and therefore an important reduction in the costs connected withthe raw materials is obtained.

In addition, the tray is obtained by simple folding operations thatcould possibly be made by a single production machine during fewoperating steps in succession.

The structure of the tray as made allows an excellent resistance tostresses transverse to the side walls and in addition no gluing regionsare present at the foodstuff-holding space.

Due to the absence of any cut, hole or the like, the paper material isinhibited from getting into contact with the humidity or water containedin the foods, which could weaken it and make the tray lose itsstructural features.

The container of the invention is very practical, can be piled up andcan be easily reproduced and is also provided with the necessary flatsurfaces for carrying out heat-sealing of plastic closure films forconservation of the foods contained therein.

1. A tray for foodstuff of sheet paper material comprising: a bottom(2); a side wall (3) defined by straight portions (4) and curvedportions (5) and emerging from the bottom, said side wall defining, incooperation with the bottom itself, a holding space (6) facingupwardly-under use conditions of the tray, wherein at least one straightportion (4) of the side wall (3) has an upper region comprising anupwardly-facing flat surface (7) and a reinforcing tab (8) associatedwith the first flat surface (7) in the assembled conditions of the tray,at least one curved portion (5) of the side wall comprising anupwardly-facing flat surface (9), at least one straight portion (4) andone curved portion (5) of the side wall (3) having respectivereinforcing edges (10) folded transversely of the flat surfaces (7, 9),said bottom (2), side wall (3), straight portions (4), curved portions(5), flat surfaces (7, 9), tabs and reinforcing edges (8, 10) beingdefined by the same sheet of paper material.
 2. A tray as claimed inclaim 1, wherein the straight and curved portions (4, 5) of the sidewall (3) define an inner holding surface (11) without a break oropening.
 3. A tray as claimed in claim 1, wherein the bottom (2) is of arectangular shape the sides of which are connected with each other bycurved sections.
 4. A tray as claimed in claim 1, wherein the flatsurfaces (7, 9) of the straight (4) and curved (5) portions define asurface without a break and are set to receive a heat-sealed film forclosure of the holding space.
 5. A tray as claimed in claim 3, whereinall the straight portions (4) comprise said first upwardly-facing flatsurface (7) and the reinforcing tab (8) associated with the first flatsurface (7) in an assembled condition of the tray.
 6. A tray as claimedin claim 3, wherein all the curved portions emerging from the curvedsections of the bottom (2) comprise the upwardly-facing flat surface(9).
 7. A tray as claimed in claim 1, wherein the flat surface (7) andreinforcing tab (8) of each straight portion (4) are not separatedelements and are joined together without a break.
 8. A tray as claimedin claim 1, wherein the reinforcing edge (10) is defined along the wholeupper perimeter of the tray and is without a break over the wholeextension thereof.
 9. A tray as claimed in claim 1, wherein thereinforcing edge (10) has a double wall at the straight portions (4).10. A tray as claimed in claim 4, wherein the tray is fully madestarting from a single plain sheet of paper material.
 11. A tray asclaimed in claim 1, wherein the tray has no further elements of papermaterial added thereto by gluing, stapling or mechanical means to definethe structure or structural resistance features of the tray.
 12. A trayas claimed in claim 1, wherein the reinforcing tab (8) comprises endportions (8A) designed to abut against the lower side of the flatsurfaces (9) of the curved portions (5).
 13. A tray for foodstuffs madeof paper material comprising: a bottom (2); a side wall (3) havingstraight portions (4) and curved portions (5) alternated one to theother, the side wall (3) emerging from the bottom (2) and defining, incooperation with the bottom, a holding space (6) facing upwardly underuse condition of the tray, wherein each straight portion (4) and curvedportion (5) of the side wall (3) has an upper region comprisingupwardly-facing flat surfaces (7, 9) and respective reinforcing edges(10) folded transversely of the flat surfaces (7, 9), each upper regionof the straight portion (4) further comprising a reinforcing tab (8)having a first element parallel and joined to the upwardly-facingsurface (7) and a second element parallel and joined to the reinforcingedges (10).
 14. Tray according to claim 13, wherein the reinforcing tab(8) comprises end portions (8a) having a first element parallel andjoined to the upwardly-facing surface (9) of the curved portion (5) anda second element parallel and joined to the reinforcing edge (10) of thecurved portion (5).
 15. A tray for foodstuffs entirely made of a sheetpaper material, the sheet paper material comprising: a central area ofrectangular shape, the four sides of which are connected with each otherby curved sections; four rectangular elements emerging from the centralarea in correspondence of the four sides; four curved elements emergingfrom the central area and connecting the four rectangular elements; aperipheral strip having constant and containing the central area, thefour rectangular elements and the four curved elements, the peripheralstrip being defined by four straight strips alternated to four curvedstrips; and four reinforcing edges emerging from and exclusivelyconnected to the four straight strips, the central area, the rectangularelements, the curved elements, the peripheral strip and the reinforcingedges being a simple piece element of paper.